How to have the camera move when mouse is moved toward a screen edge, using addForce, around a globe

Hi, I've hit a wall trying to figure out a control system for my first game.

I have a camera attached to a rigidbody Player which is looking down at a globe (using a gravity system).

Here's what I'm attempting to achieve:

The player/camera needs to move based on the mouse position--how close it is to the edge of the screen. Eventually this will be based on phone tilt using the gyroscope, but until then I need a way to test it.

I want to use AddForce (acceleration?), rather than mouse speed, because the player is a rigidbody and I want the movement to complement the gravity which is constantly pulling the player down.

The camera needs to move left, right, up, down, relative to the player/camera object, because the player/camera is constantly oriented toward the globe.

So, basically i want to push the camera around using force.

A hint or some guidance would be very appreciated!